Line data Source code
1 : /*
2 : * EAP peer method: EAP-PSK (RFC 4764)
3 : * Copyright (c) 2004-2008, Jouni Malinen <j@w1.fi>
4 : *
5 : * This software may be distributed under the terms of the BSD license.
6 : * See README for more details.
7 : *
8 : * Note: EAP-PSK is an EAP authentication method and as such, completely
9 : * different from WPA-PSK. This file is not needed for WPA-PSK functionality.
10 : */
11 :
12 : #include "includes.h"
13 :
14 : #include "common.h"
15 : #include "crypto/aes_wrap.h"
16 : #include "crypto/random.h"
17 : #include "eap_common/eap_psk_common.h"
18 : #include "eap_i.h"
19 :
20 :
21 : struct eap_psk_data {
22 : enum { PSK_INIT, PSK_MAC_SENT, PSK_DONE } state;
23 : u8 rand_p[EAP_PSK_RAND_LEN];
24 : u8 rand_s[EAP_PSK_RAND_LEN];
25 : u8 ak[EAP_PSK_AK_LEN], kdk[EAP_PSK_KDK_LEN], tek[EAP_PSK_TEK_LEN];
26 : u8 *id_s, *id_p;
27 : size_t id_s_len, id_p_len;
28 : u8 msk[EAP_MSK_LEN];
29 : u8 emsk[EAP_EMSK_LEN];
30 : };
31 :
32 :
33 18 : static void * eap_psk_init(struct eap_sm *sm)
34 : {
35 : struct eap_psk_data *data;
36 : const u8 *identity, *password;
37 : size_t identity_len, password_len;
38 :
39 18 : password = eap_get_config_password(sm, &password_len);
40 18 : if (!password || password_len != 16) {
41 0 : wpa_printf(MSG_INFO, "EAP-PSK: 16-octet pre-shared key not "
42 : "configured");
43 0 : return NULL;
44 : }
45 :
46 18 : data = os_zalloc(sizeof(*data));
47 18 : if (data == NULL)
48 0 : return NULL;
49 18 : if (eap_psk_key_setup(password, data->ak, data->kdk)) {
50 0 : os_free(data);
51 0 : return NULL;
52 : }
53 18 : wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: AK", data->ak, EAP_PSK_AK_LEN);
54 18 : wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: KDK", data->kdk, EAP_PSK_KDK_LEN);
55 18 : data->state = PSK_INIT;
56 :
57 18 : identity = eap_get_config_identity(sm, &identity_len);
58 18 : if (identity) {
59 18 : data->id_p = os_malloc(identity_len);
60 18 : if (data->id_p)
61 18 : os_memcpy(data->id_p, identity, identity_len);
62 18 : data->id_p_len = identity_len;
63 : }
64 18 : if (data->id_p == NULL) {
65 0 : wpa_printf(MSG_INFO, "EAP-PSK: could not get own identity");
66 0 : os_free(data);
67 0 : return NULL;
68 : }
69 :
70 18 : return data;
71 : }
72 :
73 :
74 18 : static void eap_psk_deinit(struct eap_sm *sm, void *priv)
75 : {
76 18 : struct eap_psk_data *data = priv;
77 18 : os_free(data->id_s);
78 18 : os_free(data->id_p);
79 18 : os_free(data);
80 18 : }
81 :
82 :
83 18 : static struct wpabuf * eap_psk_process_1(struct eap_psk_data *data,
84 : struct eap_method_ret *ret,
85 : const struct wpabuf *reqData)
86 : {
87 : const struct eap_psk_hdr_1 *hdr1;
88 : struct eap_psk_hdr_2 *hdr2;
89 : struct wpabuf *resp;
90 : u8 *buf, *pos;
91 : size_t buflen, len;
92 : const u8 *cpos;
93 :
94 18 : wpa_printf(MSG_DEBUG, "EAP-PSK: in INIT state");
95 :
96 18 : cpos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, reqData, &len);
97 18 : hdr1 = (const struct eap_psk_hdr_1 *) cpos;
98 18 : if (cpos == NULL || len < sizeof(*hdr1)) {
99 0 : wpa_printf(MSG_INFO, "EAP-PSK: Invalid first message "
100 : "length (%lu; expected %lu or more)",
101 : (unsigned long) len,
102 : (unsigned long) sizeof(*hdr1));
103 0 : ret->ignore = TRUE;
104 0 : return NULL;
105 : }
106 18 : wpa_printf(MSG_DEBUG, "EAP-PSK: Flags=0x%x", hdr1->flags);
107 18 : if (EAP_PSK_FLAGS_GET_T(hdr1->flags) != 0) {
108 0 : wpa_printf(MSG_INFO, "EAP-PSK: Unexpected T=%d (expected 0)",
109 0 : EAP_PSK_FLAGS_GET_T(hdr1->flags));
110 0 : ret->methodState = METHOD_DONE;
111 0 : ret->decision = DECISION_FAIL;
112 0 : return NULL;
113 : }
114 18 : wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_S", hdr1->rand_s,
115 : EAP_PSK_RAND_LEN);
116 18 : os_memcpy(data->rand_s, hdr1->rand_s, EAP_PSK_RAND_LEN);
117 18 : os_free(data->id_s);
118 18 : data->id_s_len = len - sizeof(*hdr1);
119 18 : data->id_s = os_malloc(data->id_s_len);
120 18 : if (data->id_s == NULL) {
121 0 : wpa_printf(MSG_ERROR, "EAP-PSK: Failed to allocate memory for "
122 : "ID_S (len=%lu)", (unsigned long) data->id_s_len);
123 0 : ret->ignore = TRUE;
124 0 : return NULL;
125 : }
126 18 : os_memcpy(data->id_s, (u8 *) (hdr1 + 1), data->id_s_len);
127 36 : wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: ID_S",
128 18 : data->id_s, data->id_s_len);
129 :
130 18 : if (random_get_bytes(data->rand_p, EAP_PSK_RAND_LEN)) {
131 0 : wpa_printf(MSG_ERROR, "EAP-PSK: Failed to get random data");
132 0 : ret->ignore = TRUE;
133 0 : return NULL;
134 : }
135 :
136 36 : resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PSK,
137 18 : sizeof(*hdr2) + data->id_p_len, EAP_CODE_RESPONSE,
138 18 : eap_get_id(reqData));
139 18 : if (resp == NULL)
140 0 : return NULL;
141 18 : hdr2 = wpabuf_put(resp, sizeof(*hdr2));
142 18 : hdr2->flags = EAP_PSK_FLAGS_SET_T(1); /* T=1 */
143 18 : os_memcpy(hdr2->rand_s, hdr1->rand_s, EAP_PSK_RAND_LEN);
144 18 : os_memcpy(hdr2->rand_p, data->rand_p, EAP_PSK_RAND_LEN);
145 18 : wpabuf_put_data(resp, data->id_p, data->id_p_len);
146 : /* MAC_P = OMAC1-AES-128(AK, ID_P||ID_S||RAND_S||RAND_P) */
147 18 : buflen = data->id_p_len + data->id_s_len + 2 * EAP_PSK_RAND_LEN;
148 18 : buf = os_malloc(buflen);
149 18 : if (buf == NULL) {
150 0 : wpabuf_free(resp);
151 0 : return NULL;
152 : }
153 18 : os_memcpy(buf, data->id_p, data->id_p_len);
154 18 : pos = buf + data->id_p_len;
155 18 : os_memcpy(pos, data->id_s, data->id_s_len);
156 18 : pos += data->id_s_len;
157 18 : os_memcpy(pos, hdr1->rand_s, EAP_PSK_RAND_LEN);
158 18 : pos += EAP_PSK_RAND_LEN;
159 18 : os_memcpy(pos, data->rand_p, EAP_PSK_RAND_LEN);
160 18 : if (omac1_aes_128(data->ak, buf, buflen, hdr2->mac_p)) {
161 0 : os_free(buf);
162 0 : wpabuf_free(resp);
163 0 : return NULL;
164 : }
165 18 : os_free(buf);
166 18 : wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_P", hdr2->rand_p,
167 : EAP_PSK_RAND_LEN);
168 18 : wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_P", hdr2->mac_p, EAP_PSK_MAC_LEN);
169 36 : wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: ID_P",
170 18 : data->id_p, data->id_p_len);
171 :
172 18 : data->state = PSK_MAC_SENT;
173 :
174 18 : return resp;
175 : }
176 :
177 :
178 17 : static struct wpabuf * eap_psk_process_3(struct eap_psk_data *data,
179 : struct eap_method_ret *ret,
180 : const struct wpabuf *reqData)
181 : {
182 : const struct eap_psk_hdr_3 *hdr3;
183 : struct eap_psk_hdr_4 *hdr4;
184 : struct wpabuf *resp;
185 : u8 *buf, *rpchannel, nonce[16], *decrypted;
186 : const u8 *pchannel, *tag, *msg;
187 : u8 mac[EAP_PSK_MAC_LEN];
188 : size_t buflen, left, data_len, len, plen;
189 17 : int failed = 0;
190 : const u8 *pos;
191 :
192 17 : wpa_printf(MSG_DEBUG, "EAP-PSK: in MAC_SENT state");
193 :
194 17 : pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK,
195 : reqData, &len);
196 17 : hdr3 = (const struct eap_psk_hdr_3 *) pos;
197 17 : if (pos == NULL || len < sizeof(*hdr3)) {
198 0 : wpa_printf(MSG_INFO, "EAP-PSK: Invalid third message "
199 : "length (%lu; expected %lu or more)",
200 : (unsigned long) len,
201 : (unsigned long) sizeof(*hdr3));
202 0 : ret->ignore = TRUE;
203 0 : return NULL;
204 : }
205 17 : left = len - sizeof(*hdr3);
206 17 : pchannel = (const u8 *) (hdr3 + 1);
207 17 : wpa_printf(MSG_DEBUG, "EAP-PSK: Flags=0x%x", hdr3->flags);
208 17 : if (EAP_PSK_FLAGS_GET_T(hdr3->flags) != 2) {
209 0 : wpa_printf(MSG_INFO, "EAP-PSK: Unexpected T=%d (expected 2)",
210 0 : EAP_PSK_FLAGS_GET_T(hdr3->flags));
211 0 : ret->methodState = METHOD_DONE;
212 0 : ret->decision = DECISION_FAIL;
213 0 : return NULL;
214 : }
215 17 : wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_S", hdr3->rand_s,
216 : EAP_PSK_RAND_LEN);
217 17 : wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_S", hdr3->mac_s, EAP_PSK_MAC_LEN);
218 17 : wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL", pchannel, left);
219 :
220 17 : if (left < 4 + 16 + 1) {
221 0 : wpa_printf(MSG_INFO, "EAP-PSK: Too short PCHANNEL data in "
222 : "third message (len=%lu, expected 21)",
223 : (unsigned long) left);
224 0 : ret->ignore = TRUE;
225 0 : return NULL;
226 : }
227 :
228 : /* MAC_S = OMAC1-AES-128(AK, ID_S||RAND_P) */
229 17 : buflen = data->id_s_len + EAP_PSK_RAND_LEN;
230 17 : buf = os_malloc(buflen);
231 17 : if (buf == NULL)
232 0 : return NULL;
233 17 : os_memcpy(buf, data->id_s, data->id_s_len);
234 17 : os_memcpy(buf + data->id_s_len, data->rand_p, EAP_PSK_RAND_LEN);
235 17 : if (omac1_aes_128(data->ak, buf, buflen, mac)) {
236 0 : os_free(buf);
237 0 : return NULL;
238 : }
239 17 : os_free(buf);
240 17 : if (os_memcmp(mac, hdr3->mac_s, EAP_PSK_MAC_LEN) != 0) {
241 0 : wpa_printf(MSG_WARNING, "EAP-PSK: Invalid MAC_S in third "
242 : "message");
243 0 : ret->methodState = METHOD_DONE;
244 0 : ret->decision = DECISION_FAIL;
245 0 : return NULL;
246 : }
247 17 : wpa_printf(MSG_DEBUG, "EAP-PSK: MAC_S verified successfully");
248 :
249 17 : if (eap_psk_derive_keys(data->kdk, data->rand_p, data->tek,
250 17 : data->msk, data->emsk)) {
251 0 : ret->methodState = METHOD_DONE;
252 0 : ret->decision = DECISION_FAIL;
253 0 : return NULL;
254 : }
255 17 : wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: TEK", data->tek, EAP_PSK_TEK_LEN);
256 17 : wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: MSK", data->msk, EAP_MSK_LEN);
257 17 : wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: EMSK", data->emsk, EAP_EMSK_LEN);
258 :
259 17 : os_memset(nonce, 0, 12);
260 17 : os_memcpy(nonce + 12, pchannel, 4);
261 17 : pchannel += 4;
262 17 : left -= 4;
263 :
264 17 : tag = pchannel;
265 17 : pchannel += 16;
266 17 : left -= 16;
267 :
268 17 : msg = pchannel;
269 :
270 17 : wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - nonce",
271 : nonce, sizeof(nonce));
272 17 : wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - hdr",
273 : wpabuf_head(reqData), 5);
274 17 : wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - cipher msg", msg, left);
275 :
276 17 : decrypted = os_malloc(left);
277 17 : if (decrypted == NULL) {
278 0 : ret->methodState = METHOD_DONE;
279 0 : ret->decision = DECISION_FAIL;
280 0 : return NULL;
281 : }
282 17 : os_memcpy(decrypted, msg, left);
283 :
284 17 : if (aes_128_eax_decrypt(data->tek, nonce, sizeof(nonce),
285 17 : wpabuf_head(reqData),
286 : sizeof(struct eap_hdr) + 1 +
287 : sizeof(*hdr3) - EAP_PSK_MAC_LEN, decrypted,
288 : left, tag)) {
289 0 : wpa_printf(MSG_WARNING, "EAP-PSK: PCHANNEL decryption failed");
290 0 : os_free(decrypted);
291 0 : return NULL;
292 : }
293 17 : wpa_hexdump(MSG_DEBUG, "EAP-PSK: Decrypted PCHANNEL message",
294 : decrypted, left);
295 :
296 : /* Verify R flag */
297 17 : switch (decrypted[0] >> 6) {
298 : case EAP_PSK_R_FLAG_CONT:
299 0 : wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - CONT - unsupported");
300 0 : failed = 1;
301 0 : break;
302 : case EAP_PSK_R_FLAG_DONE_SUCCESS:
303 17 : wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_SUCCESS");
304 17 : break;
305 : case EAP_PSK_R_FLAG_DONE_FAILURE:
306 0 : wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_FAILURE");
307 0 : wpa_printf(MSG_INFO, "EAP-PSK: Authentication server rejected "
308 : "authentication");
309 0 : failed = 1;
310 0 : break;
311 : }
312 :
313 17 : data_len = 1;
314 17 : if ((decrypted[0] & EAP_PSK_E_FLAG) && left > 1)
315 0 : data_len++;
316 17 : plen = sizeof(*hdr4) + 4 + 16 + data_len;
317 17 : resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PSK, plen,
318 17 : EAP_CODE_RESPONSE, eap_get_id(reqData));
319 17 : if (resp == NULL) {
320 0 : os_free(decrypted);
321 0 : return NULL;
322 : }
323 17 : hdr4 = wpabuf_put(resp, sizeof(*hdr4));
324 17 : hdr4->flags = EAP_PSK_FLAGS_SET_T(3); /* T=3 */
325 17 : os_memcpy(hdr4->rand_s, hdr3->rand_s, EAP_PSK_RAND_LEN);
326 17 : rpchannel = wpabuf_put(resp, 4 + 16 + data_len);
327 :
328 : /* nonce++ */
329 17 : inc_byte_array(nonce, sizeof(nonce));
330 17 : os_memcpy(rpchannel, nonce + 12, 4);
331 :
332 17 : if (decrypted[0] & EAP_PSK_E_FLAG) {
333 0 : wpa_printf(MSG_DEBUG, "EAP-PSK: Unsupported E (Ext) flag");
334 0 : failed = 1;
335 0 : rpchannel[4 + 16] = (EAP_PSK_R_FLAG_DONE_FAILURE << 6) |
336 : EAP_PSK_E_FLAG;
337 0 : if (left > 1) {
338 : /* Add empty EXT_Payload with same EXT_Type */
339 0 : rpchannel[4 + 16 + 1] = decrypted[1];
340 : }
341 17 : } else if (failed)
342 0 : rpchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_FAILURE << 6;
343 : else
344 17 : rpchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_SUCCESS << 6;
345 :
346 17 : wpa_hexdump(MSG_DEBUG, "EAP-PSK: reply message (plaintext)",
347 : rpchannel + 4 + 16, data_len);
348 34 : if (aes_128_eax_encrypt(data->tek, nonce, sizeof(nonce),
349 17 : wpabuf_head(resp),
350 : sizeof(struct eap_hdr) + 1 + sizeof(*hdr4),
351 : rpchannel + 4 + 16, data_len, rpchannel + 4)) {
352 0 : os_free(decrypted);
353 0 : wpabuf_free(resp);
354 0 : return NULL;
355 : }
356 17 : wpa_hexdump(MSG_DEBUG, "EAP-PSK: reply message (PCHANNEL)",
357 : rpchannel, 4 + 16 + data_len);
358 :
359 17 : wpa_printf(MSG_DEBUG, "EAP-PSK: Completed %ssuccessfully",
360 : failed ? "un" : "");
361 17 : data->state = PSK_DONE;
362 17 : ret->methodState = METHOD_DONE;
363 17 : ret->decision = failed ? DECISION_FAIL : DECISION_UNCOND_SUCC;
364 :
365 17 : os_free(decrypted);
366 :
367 17 : return resp;
368 : }
369 :
370 :
371 35 : static struct wpabuf * eap_psk_process(struct eap_sm *sm, void *priv,
372 : struct eap_method_ret *ret,
373 : const struct wpabuf *reqData)
374 : {
375 35 : struct eap_psk_data *data = priv;
376 : const u8 *pos;
377 35 : struct wpabuf *resp = NULL;
378 : size_t len;
379 :
380 35 : pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, reqData, &len);
381 35 : if (pos == NULL) {
382 0 : ret->ignore = TRUE;
383 0 : return NULL;
384 : }
385 :
386 35 : ret->ignore = FALSE;
387 35 : ret->methodState = METHOD_MAY_CONT;
388 35 : ret->decision = DECISION_FAIL;
389 35 : ret->allowNotifications = TRUE;
390 :
391 35 : switch (data->state) {
392 : case PSK_INIT:
393 18 : resp = eap_psk_process_1(data, ret, reqData);
394 18 : break;
395 : case PSK_MAC_SENT:
396 17 : resp = eap_psk_process_3(data, ret, reqData);
397 17 : break;
398 : case PSK_DONE:
399 0 : wpa_printf(MSG_DEBUG, "EAP-PSK: in DONE state - ignore "
400 : "unexpected message");
401 0 : ret->ignore = TRUE;
402 0 : return NULL;
403 : }
404 :
405 35 : if (ret->methodState == METHOD_DONE) {
406 17 : ret->allowNotifications = FALSE;
407 : }
408 :
409 35 : return resp;
410 : }
411 :
412 :
413 35 : static Boolean eap_psk_isKeyAvailable(struct eap_sm *sm, void *priv)
414 : {
415 35 : struct eap_psk_data *data = priv;
416 35 : return data->state == PSK_DONE;
417 : }
418 :
419 :
420 17 : static u8 * eap_psk_getKey(struct eap_sm *sm, void *priv, size_t *len)
421 : {
422 17 : struct eap_psk_data *data = priv;
423 : u8 *key;
424 :
425 17 : if (data->state != PSK_DONE)
426 0 : return NULL;
427 :
428 17 : key = os_malloc(EAP_MSK_LEN);
429 17 : if (key == NULL)
430 0 : return NULL;
431 :
432 17 : *len = EAP_MSK_LEN;
433 17 : os_memcpy(key, data->msk, EAP_MSK_LEN);
434 :
435 17 : return key;
436 : }
437 :
438 :
439 17 : static u8 * eap_psk_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
440 : {
441 17 : struct eap_psk_data *data = priv;
442 : u8 *id;
443 :
444 17 : if (data->state != PSK_DONE)
445 0 : return NULL;
446 :
447 17 : *len = 1 + 2 * EAP_PSK_RAND_LEN;
448 17 : id = os_malloc(*len);
449 17 : if (id == NULL)
450 0 : return NULL;
451 :
452 17 : id[0] = EAP_TYPE_PSK;
453 17 : os_memcpy(id + 1, data->rand_p, EAP_PSK_RAND_LEN);
454 17 : os_memcpy(id + 1 + EAP_PSK_RAND_LEN, data->rand_s, EAP_PSK_RAND_LEN);
455 17 : wpa_hexdump(MSG_DEBUG, "EAP-PSK: Derived Session-Id", id, *len);
456 :
457 17 : return id;
458 : }
459 :
460 :
461 0 : static u8 * eap_psk_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
462 : {
463 0 : struct eap_psk_data *data = priv;
464 : u8 *key;
465 :
466 0 : if (data->state != PSK_DONE)
467 0 : return NULL;
468 :
469 0 : key = os_malloc(EAP_EMSK_LEN);
470 0 : if (key == NULL)
471 0 : return NULL;
472 :
473 0 : *len = EAP_EMSK_LEN;
474 0 : os_memcpy(key, data->emsk, EAP_EMSK_LEN);
475 :
476 0 : return key;
477 : }
478 :
479 :
480 4 : int eap_peer_psk_register(void)
481 : {
482 : struct eap_method *eap;
483 : int ret;
484 :
485 4 : eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
486 : EAP_VENDOR_IETF, EAP_TYPE_PSK, "PSK");
487 4 : if (eap == NULL)
488 0 : return -1;
489 :
490 4 : eap->init = eap_psk_init;
491 4 : eap->deinit = eap_psk_deinit;
492 4 : eap->process = eap_psk_process;
493 4 : eap->isKeyAvailable = eap_psk_isKeyAvailable;
494 4 : eap->getKey = eap_psk_getKey;
495 4 : eap->getSessionId = eap_psk_get_session_id;
496 4 : eap->get_emsk = eap_psk_get_emsk;
497 :
498 4 : ret = eap_peer_method_register(eap);
499 4 : if (ret)
500 0 : eap_peer_method_free(eap);
501 4 : return ret;
502 : }
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